Association Between Phasic Vagal-Mediated Heart Rate Variability and Momentary Exhaustion in Daily Life.

Stress-related chronic exhaustion can be predicted longitudinally by reduced basic vagal tone (i.e., vagally-mediated heart rate variability [vmHRV]). However, little is known about the relationship between phasic vmHRV and momentary exhaustion in daily life. To examine this relationship, this preregistered study used ecological momentary assessment (EMA) in a sample of N = 151 healthy participants (age = 22.17 years [SD = 4.98 years]; 14.57% male) for three consecutive weekdays. Exploratorily, we examined if individuals with higher chronic exhaustion would show different patterns of phasic vmHRV when perceiving acute stress. We analysed data on momentary (emotional, cognitive, physical) exhaustion, perceived acute stress, ambulatory ECG data and adjusted for relevant covariates (e.g., age, gender, and momentary movement acceleration) using multi-level analyses. After adjusting for preregistered covariates, phasic vmHRV showed a positive association with momentary emotional and cognitive exhaustion, but not with momentary physical exhaustion. Our exploratory analyses revealed that individuals with higher levels of chronic exhaustion did not show the expected negative association between situationally perceived acute stress and phasic vmHRV, whereas those with lover levels did. These findings indicate that momentary exhaustion is associated with increased phasic vmHRV in daily life. Combined with our exploratory results that chronic exhaustion modulates vagal withdrawal under perceived acute stress, this study offers important directions for future research into the link between stress-related exhaustion and autonomic changes. Study Registration: The study and analysis plan were preregistered at OSF (DOI: 10.17605/OSF.IO/T2C4X).